The subject matter disclosed herein relates to a valve and in particular to a butterfly valve having a retainer for a ring seal.
Butterfly valves are used in a wide variety of applications to control the flow of fluids. A butterfly valve typically has a disk member arranged in the flow of the fluid. The disk rotates between an open position where fluid flows and a closed position against a valve seat where fluid flow is stopped. A seal member is arranged about an outer periphery of the disk that engages the valve seat to prevent the flow of fluid when the valve is in a closed position.
In some high temperature applications, such as in aircraft for example, butterfly valves have historically performed poorly with reliability issues of slow or inaccurate operation that in some circumstances may result in the jamming of the valve or breaking of the seal ring. These issues are heightened in larger butterfly valves, such as those that are 3 inches (7.62 centimeters) or larger. The causes of these reliability issues may be attributed to several factors. Due to the high temperature environment, the seal ring is typically made from metals that have no natural lubricity and traditional plating processes, such as hard chrome plating for example, may no longer be used due to environmental concerns. Other secondary lubrication materials such as dry film lubricants for example have short effective lives.
Another factor that may lead to a reliability issue is the means by which the seal ring is retained in the disk. Some configurations allow the seal ring to rotate freely to alleviate friction issues, but include latching features to prevent excessive radial movement. These latch features significantly weaken the seal ring. Other configurations have non-rotating seal rings that increase friction issues. Still other configurations allow for the use of carbon material for the seal ring, but utilize complicated and heavy multi-piece disk designs.
Accordingly, while existing butterfly valves are suitable for their intended purposes the need for improvement remains, particularly in a butterfly valve having a disk with a freely rotating seal ring.